Fibromyalgia

Basics

Description

  • Nonarticular, noninflammatory form of muscular and joint pain more common in females:
    • Widespread pain from stimuli that do not normally cause pain (allodynia)
    • ≥6 sites of pain involved
    • Chronic fatigue
    • Headaches
    • Frequent awakenings during sleep
    • Arthralgia and myalgia
    • Inattention, memory loss, brain fog
    • Usually no physical findings
  • Often coexists with other conditions (ie, obstructive sleep apnea, chronic fatigue syndrome, temporomandibular disorders)

Etiology

  • Mechanism is thought to be multifactorial including:
    • Genetics:
      • No specific gene identified
      • Younger onset generally indicates stronger genetic component
      • Possibly involves genes of serotonin, mu-opioid, GABA, or catecholamine metabolism
    • Central sensitization:
      • Increased perceived intensity of pain
      • Decreased endogenous analgesic systems
      • Upregulated peripheral opioid receptors
    • Peripheral nociceptors:
      • Nociplastic pain – pain from altered nociception in absence of actual tissue damage
      • Possible association with small fiber neuropathy with demonstration of reduced intraepidermal nerve fiber density or electrochemical skin conductance
      • Often have hyperesthesia in a stocking distribution
      • Lower concentrations of ATP and phosphocreatine in skeletal muscle has been demonstrated
    • Hypothalamus–pituitary–adrenal axis stress-responsive dysfunction has been indicated to precede development of FM:
      • Possibly due to increased serum cortisol

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